In our recent blog, Choosing a Linear Accelerator: The Evolving Landscape in 2025, we explored the wide range of new and emerging linac platforms on the global market. But when it comes to Varian systems, two options continue to dominate facility shortlists: the TrueBeam and the Halcyon. 

Both offer advanced radiation therapy capabilities, but each was built with different clinical needs in mind. TrueBeam is known for its precision and flexibility, while Halcyon delivers efficiency and ease of use. While both systems serve a purpose, many clinics ultimately find TrueBeam to be the more strategic, long-term solution. This blog provides a side-by-side comparison of their differences, enabling radiation oncology teams to determine which system best aligns with their clinical, operational, and financial objectives. 

Overview of Varian’s TrueBeam and Halcyon Linear Accelerators

TrueBeam was introduced in 2010 as a high-precision platform for image-guided radiotherapy and radiosurgery. It quickly became the workhorse system for clinics needing a versatile linac that could deliver a wide range of treatments, from conventional 3D to SBRT and SRS. 

Halcyon, launched in 2017, was designed with a different goal in mind: to streamline workflow and expand access to high-quality radiation therapy in high-volume or resource-limited settings. It offers a simplified, tunnel-style design that supports rapid treatment planning and delivery. 

According to public sources, more than 3,000 TrueBeam systems have been installed globally as of 2019. While Halcyon adoption is growing, specific numbers are limited in publicly available data. 

TrueBeam vs. Halcyon: Comparing Treatment Capabilities

TrueBeam delivers strong clinical versatility, supporting a wide range of photon and electron energies for advanced treatments, including SRS, SBRT, and total body irradiation. It is compatible with multiple imaging modes, including respiratory gating, and enables radiation delivery from various angles around the patient. These features make it well-suited for complex or mobile tumors, as well as for clinics aiming to offer a broad spectrum of treatment protocols. 

Halcyon is designed with efficiency in mind. It performs best in high-throughput environments where fast, standardized treatments are the priority. With a simplified imaging system and fixed beam geometry, Halcyon limits some of the advanced motion management and positioning flexibility found in TrueBeam. However, for clinics focused on routine cases and expedited treatment delivery, it offers a more streamlined and cost-effective option.

Clinical Applications: How TrueBeam and Halcyon Are Used in Practice 

Clinical studies have shown Halcyon to be effective in treating common cancers, such as: 

• Early-stage breast cancer, using a hybrid technique that shortens treatment time while maintaining clinical outcomes. 

• Prostate cancer, using SBRT for precise dose delivery and favorable results. 

TrueBeam is also widely used for standard treatments and provides added flexibility in more complex clinical cases: 

• Breast and skin cancer, TrueBeam’s Flattening Filter Free (FFF) beam delivers precise radiation to the tumor while reducing exposure to nearby organs like the heart and lungs. 

• Early-stage lung cancer, studies show that TrueBeam can provide high local control and low side effects using SBRT. 

While Halcyon works well for routine cases, TrueBeam can handle those same cases and supports more complex treatments when needed. 

Advanced Capabilities: What Sets TrueBeam Apart 

Facilities evaluating either system should consider not only initial cost, but also treatment versatility, upgrade potential, and long-term service strategy. For example, TrueBeam has been used successfully in single-isocenter SRS for multiple brain metastases—an advanced treatment technique that Halcyon cannot deliver due to its coplanar-only limitations. Clinics looking to expand into advanced radiosurgery programs or high-precision, motion-managed treatments will likely benefit from TrueBeam’s broader capabilities. 

How Do TrueBeam and Halcyon Compare in Patient Comfort? 

Beyond clinical capabilities, the design of each system affects the patient experience. The tunnel-style Halcyon may feel more enclosed, which can be mildly claustrophobic for some individuals. In contrast, the open configuration of TrueBeam provides a more spacious treatment environment. For clinics that prioritize patient comfort, especially when treating anxious or pediatric patients, this design difference may be an essential consideration.

Pre-Owned TrueBeam Linear Accelerators: A Cost-Effective Solution 

For clinics looking to expand access to quality care without the high price tag of a new system, pre-owned TrueBeams offer a practical and proven option. These systems are often available sooner than new units and come with the core features clinics need to treat a wide range of patients. 

Halcyon systems, by comparison, are rarely found on the secondary market as of 2025, making pre-owned availability an added advantage for facilities considering TrueBeam. 

Should You Choose TrueBeam or Halcyon for Your Clinic? 

TrueBeam combines advanced imaging, broad energy selection, and upgrade flexibility, making it ideal for facilities that want to offer a wide range of treatments today and preserve room to grow tomorrow. 

Halcyon focuses on speed and simplicity. For clinics centered on standard treatments and efficient workflows, its lower upfront cost and streamlined design may be an appropriate fit. 

Facilities that weigh long-term clinical versatility alongside operational needs often find TrueBeam to be the more comprehensive solution. Contact us to learn more about selecting the right system for your facility. 

Frequently Asked Questions 

What is the main difference between TrueBeam and Halcyon?

TrueBeam supports a broader range of treatments, including complex cases, while Halcyon is optimized for speed and efficiency in standardized treatments. 

Does Halcyon support  SRS or SBRT treatments?

Halcyon can perform SBRT in select cases, such as prostate cancer, but does not support SRS due to its fixed-beam geometry. 

Can I buy a pre-owned Varian TrueBeam linear accelerator?

Yes. Pre-owned TrueBeam systems are available through trusted providers and offer a reliable, lower-cost alternative for clinics seeking advanced treatment capabilities.. 

Can TrueBeam or Halcyon be used with AI treatment planning software?

Yes. Both systems can integrate with AI  planning tools, though TrueBeam’s advanced imaging and motion capabilities provide more flexibility for AI-optimized treatments. Halcyon can also be upgraded to Ethos for adaptive treatment capabilities using AI.   

What energy levels do TrueBeam and Halcyon support?

TrueBeam supports multiple photon and electron energies, including flattening filter free (FFF) beams. Halcyon supports 6MV FFF photons only.